We propose to develop a novel ultra-low cost portable device for micro-SPECT/CT using clinical gamma camera detectors. Molecular imaging using micro-SPECT has emerged as a valuable tool for pre-clinical research. The ability to image small animals in-vivo and non-invasively at the molecular level with spatial resolution of 1 mm or better has many research applications in cancer, molecular cardiology, neurology, and drug discovery. The importance of micro-SPECT to research is underscored by the emergence of dedicated small animal scanners in the commercial market. However, the high costs associated with these scanners have limited this technique to established and well-funded laboratories. In our previous work, we developed a practical standalone device to be used in conjunction with a clinical gamma camera. This device is placed directly on the patient table, relying on our "auto-calibration" technique (simultaneous acquisition of emission data and point source marker data) to achieve high resolution without requiring lengthy set-up time for alignment and calibration procedures. A main disadvantage was that this previous design required the animal to be rotated in a vertical orientation, which is far from ideal. Our new proposed second-generation device allows the animal to be stationary and horizontal while preserving all the low-cost advantages of a standalone device. Our preliminary experiments have demonstrated that the auto-calibration technique is robust and accurate for this new and more complex geometry. Our first aim is to design and develop this new device and characterize its micro-SPECT performance using a standard dual-head SPECT camera. Our second aim is to acquire data on a clinical SPECT/CT scanner to produce co-registered micro-SPECT and CT images. Although the CT images do not have ultra-high spatial resolution, they are sufficient for anatomic mapping and attenuation correction of the micro-SPECT data. Our third aim is to optimize the performance through improvements in count sensitivity, image reconstruction, quantitative accuracy, and ease of use. With an estimated total manufacturing cost of under $20K, and since our device is standalone, practical, and inherently compatible with nearly all models of SPECT cameras, the long-term goal of commercialization is very feasible. Many laboratories could then benefit from this device for micro-SPECT and micro-SPECT/CT. [unreadable] [unreadable] [unreadable]